Downscaling images does not work properly with uppercase suffixes

[JasperSteringa]

Describe the bug
When using a mix of lower- and uppercase suffixes in the image dataset, the copying of images to downscaled directories will terminate once reaching a uppercase suffix.

To Reproduce
Steps to reproduce the behavior:

1. Create dataset with variation of '.jpg' and '.JPG' files
2. Run ns-process-data images on this dataset
3. Verify the content of images, as well as images_x created by ns-process-data images.
4. All files are present in images, but in images_x all files are missing after the first file with uppercase suffix.
5. ns-train will throw a FileNotFoundError, since one or more image files are missing.

Expected behavior
The downscaling by ffmpeg should be performed on files with both upper- and lowercase suffixes.

Alternative fix
ns-process-data could force the suffixes to lowercase before downscaling, i.e. when copying/renaming files to the images directory.

[JasperSteringa]

@brentyi As this is closed, has a fix been implemented?

[brentyi]

Sorry, I didn't intend to close this!!